Implementing an inverter using NAND logic In standard digital logic design, how many 2-input NAND gates are required to construct a NOT (inverter) function from a single input?

Introduction / Context:
NAND is a universal gate. Any Boolean function, including the basic NOT, AND, and OR operations, can be implemented using only NAND gates. Knowing minimal gate counts is key for cost, area, and delay optimization in logic design and discrete implementations.

Given Data / Assumptions:

• Available gate: a 2-input NAND.
• Goal: realize a NOT function (inverter) from a single input.

Concept / Approach:
The NAND truth function is Z = (A * B)'. If both inputs of a NAND are tied together to the same signal X, then Z = (X * X)' = (X)' = NOT X. Therefore, a single 2-input NAND can implement an inverter by shorting its two inputs.

Step-by-Step Solution:

Verification / Alternative check:
Truth table for X vs. Z shows X = 0 gives Z = 1; X = 1 gives Z = 0, confirming NOT behavior. This is a standard identity in universal gate constructions.

Why Other Options Are Wrong:

• 2, 3, 4 NANDs: More than necessary; a single NAND suffices when its inputs are tied together.

Common Pitfalls:
Forgetting to tie both NAND inputs together; confusing NAND-based realizations with NOR-based realizations (NOR is also universal but uses a different wiring for NOT).

Final Answer:
1